1. Technical Field
The present disclosure relates to a motor driving circuit, in particular, to a motor driving circuit which selects a Hall sensor or a Sensor-less controller to achieve the phase commutation of a magnetic pole of a motor.
2. Description of Related Art
A motor is constituted by a stator and a rotor disposed opposite to each other. The rotor can rotate with respect to the stator to operate the motor by the magnetic force and magnetic field change. The magnetic field change represents the phase commutation of the magnetic poles of the motor.
The Hall sensor is used to carry out the phase commutation in the present motor driving method. More specifically, the Hall sensor senses the positions of the magnetic poles of the motor (or the magnetic field change) so as to determine the position of the rotor. Then, the Hall sensor accordingly generates a phase switching signal to control the switch of the coil current in the stator, thereby achieving the phase commutation. With the miniaturization of the motor technology, the volume of Hall sensor has gradually decreased. However, the accuracy of the miniature Hall sensor easily suffers from temperature, noise, or other factors to influence the reliability of the commutation control. As such, the conditions and environment of where a motor is applied becomes further limited.
Another motor driving method utilizes the sensor-less controller to achieve the phase commutation of the magnetic pole of the motor. The Sensor-less controller adopts a digital signal processor (DSP) with a complex algorithm (e.g., field oriented control (FOC) and direct torque control (DTC)), and peripheral circuit to achieve the optimization control. Using the sensor-less controller can decrease time and labor cost of getting the accurate position of the sensor, and has lower cost. However, when the operation speed of the motor is lower or stops, the sensor-less controller does not adapt to the starting state because the sensor-less controller cannot measure the counter-electromotive force, initial angle, or measures the less counter-electromotive force, etc. When the motor does not have the design of an additional starting mechanism to assist the motor operating to medium-high rotational speed, the sensor-less controller cannot achieve the phase commutation of the magnetic pole of the motor.
If the motor driving circuit could select the hall sensor or the sensor-less controller to achieve the phase commutation of the magnetic pole of the motor, the motor driving circuit could select a suitable sensing device according to the motor characteristics.